Various types of acoustic devices exist and one such type of device is a microphone. In one example, the Electret Condenser Microphone (ECM) is being used in devices such as cellular phones, video cameras, studio performance microphones, and headphones to mention a few examples.
In the case of an ECM, sound energy enters through a sound port and vibrates a diaphragm and this action creates a corresponding change in electrical potential (voltage) between the diaphragm and a charge plate disposed near the diaphragm. This voltage represents the sound energy that has been received. Typically, the voltage is then transmitted to an electric circuit (e.g., an integrated circuit such as an application specific integrated circuit (ASIC)). Further processing of the signal may be performed on the electrical circuit. For instance, amplification or filtering functions may be performed on the voltage signal at the integrated circuit.
In order for the diaphragm and charge plate combination to function properly, they need to be secured within the microphone. If, for example, the distance separating them changes in an unexpected way (in the absence of the diaphragm moving in response to sound energy), then the microphone will not function properly. There are various methods to secure the diaphragm to the charge plate and the diaphragm to the housing. The connection between the charge plate and diaphragm provides mechanical support and is sometimes referred to as a “stitch”, due to its shape. The connection between the diaphragm and housing provides mechanical support and an air-tight seal around the perimeter of the diaphragm. Various attempts have been made to provide mechanical support and an air-tight seal, but these attempts have various shortcomings.
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